C-reactive protein in adolescent twins: patterns and relationship to adiposity.

CONTEXT Elevated C-reactive protein (CRP) is a marker of cardiovascular risk in adults. Patterns and determinants of CRP in adolescents have not been well described. OBJECTIVE This study aimed to determine how CRP varies by age, gender, Tanner stage, and body fat composition in rural Chinese adolescents and to what degree adiposity-CRP associations are attributable to shared genetic and environmental factors. DESIGN AND SETTING Data were derived from an ongoing study of metabolic syndrome in a large community-based twin cohort enrolled in Anqing, China. PARTICIPANTS The study sample included 1180 adolescent twins aged 13-21 yr. MAIN OUTCOME MEASURES Plasma CRP concentrations were measured by sandwich immunoassay using flow metric xMAP technology. Body fat composition was assessed by dual-energy x-ray absorptiometry. RESULTS CRP levels linearly increased across age and Tanner stage in males (P ≤ 0.0001), but in females, CRP exhibited no trend after adjusting for fat mass (P > 0.05). For males, the most explanatory measure was body mass index (partial r(2) = 5.2%), whereas percent body fat (partial r(2) = 8.8%) was more explanatory in females. Of the phenotypic correlations between adiposity measures and CRP (0.25-0.28), 86-89% were attributed to shared genetic factors and 11-14% to common unique environmental factors in both sexes. CONCLUSIONS Adiposity is a strong determinant of CRP even in this relatively lean Chinese population. There is notable gender difference for the CRP pattern and the relationship of CRP with adiposity during adolescence. To a large degree, common genetic factors may underlie the observed adiposity-CRP-phenotypic correlations.